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  Differential scanning calorimeterRelated Patent Categories: Thermal Measuring And Testing, Differential Thermal AnalysisThe Patent Description & Claims data below is from USPTO Patent Application 20070189357. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application claims priority under 35 U.S.C. .sctn.119 to Japanese Patent Application Nos. JP2006-019122 filed Jan. 27, 2006, the entire content of which is hereby incorporated by reference. BACKGROUND OF THE INVENTION [0002] The present invention is one relating to a thermal analysis apparatus measuring how physical properties of a sample change along with a temperature. Especially, it is one relating to a differential scanning calorimeter which, when the temperature has been changed, measures a heat quantity, that the sample excessively radiates or absorbs in comparison with a reference material, on the basis of a temperature difference (differential heat) between the sample and the reference material. [0003] The differential scanning calorimeter is an apparatus which, when the sample and the reference material (thermally stable material, e.g., alumina and the like) have been disposed while being juxtaposed and temperatures of both have been changed at a constant rate, differentially detects the heat quantity that the sample excessively radiates or absorbs in comparison with the reference material. [0004] As to this kind of apparatus, although various ones are provided, as one of them, there is known one having a cooling mechanism which not only heats the temperature of an accommodation chamber accommodating the sample and the reference material but also cools it. [0005] For example, there is known one having a cooling device (electric cooling device) in which a coolant is supplied to a periphery of a heating furnace which heats the sample, thereby cooling a periphery of the sample through the heating furnace (e.g., JP-B-7-65974). [0006] Further, as other apparatus, there is also known one having a cooling device (gas cooling device) in which a very low (e.g., -196.degree. C.) gas obtained by evaporating a liquefied nitrogen and the like is supplied into a sample chamber (accommodation chamber) accommodating the sample, thereby cooling a sample chamber inside (e.g., JP-B-7-122619). [0007] Additionally, there is also known one in which there are used in combination a gas cooling device performing the cooling by the very low temperature gas obtained by evaporating the liquefied nitrogen and the like, and an electric cooling device performing the cooling by compressing the coolant by a compressor and adiabatically expanding it, thereby cooling a heat sink (accommodation chamber) accommodating the sample (e.g., JP-A-2005-83763). [0008] Like this, the differential scanning calorimeter performs an analysis of the sample under various temperature conditions by freely controlling the temperature by the cooling devices of various kinds. [0009] However, in the above conventional methods, the following problems are left. [0010] That is, in the differential scanning calorimeter having the cooling device, a heat flow path that is a flow passage of a heat is secured by mechanically connecting the accommodation chamber, e.g., the heat sink, accommodating the sample and the cooling device. This is for efficiently heating and cooling the heat sink. [0011] However, the heat sink and the cooling device are not made by a material of completely the same quality, but generally are respectively made by utilizing materials of different qualities. In other words, the heat flow path is formed by mechanically connecting metals of different kinds to each other. Therefore, when analyzing the sample, if the heating and the cooling are repeatedly performed, a distortion, a deviation and the like have occurred in a joint face due to a difference in thermal expansion coefficient. As a result, a flow of the heat changes midway, so that there has existed a possibility that it is impossible to accurately perform the analysis of the sample. Further, since the distortion and the deviation change every moment in compliance with conditions at that time, a reproducibility is bad, and it has been impossible to collect a measurement result and the like. [0012] The present invention is one having been made in view of the circumstances like this, and its object is to provide a differential scanning calorimeter in which, even if the heating or the cooling has been repeatedly performed, it is possible to maintain a stable heat flow path, and which can highly precisely perform a measurement of the sample to be measured. SUMMARY OF THE INVENTION [0013] In order to solve the above problems, the present invention provides the following means. [0014] A differential scanning calorimeter of the present invention is one characterized by possessing an accommodation chamber accommodating therein a sample to be measured and a reference material, a heater attached so as to surround a periphery of the accommodation chamber to thereby heat the accommodation chamber, a differential heat flow detector which is provided in the accommodation chamber, detects a temperature difference between the sample to be measured and the reference material, and outputs the temperature difference having been detected as a heat flow difference signal, a cooling block which is disposed below the accommodation chamber while being separated by a constant distance, and cooling-controlled to a predetermined temperature, a heat resistor which is formed so as to have a predetermined heat resistance, interposed between the cooling block and the accommodation chamber to thereby mechanically connect both, and forms a heat flow path between the cooling block and the accommodation chamber, a support means supporting the cooling block, and a fixation means of at least any one between a first fixation means which fixes the heat resistor to the cooling block by pressing the former while being biased by a constant elastic force, and a second fixation means which fixes the accommodation chamber to the heat resistor by pressing the former while being biased by a constant elastic force. [0015] In the differential scanning calorimeter concerned with this invention, since it has the heater and the cooling block, by heating or cooling an object article to be measured and the reference material, which have been accommodated in the accommodation chamber, a desired temperature can be easily produced. And, the differential heat flow detector detects the temperature difference between the sample to be measured and the reference material when the temperature in the accommodation chamber has been changed, and outputs the temperature difference having been detected as the heat flow difference signal. By obtaining this heat flow difference signal, a heat quantity that the sample to be measured excessively radiates or absorbs with respect to the reference material can be differentially detected, so that it is possible to perform a thermal analysis of the sample to be measured. [0016] Here, in a case where the heater has been operated, the accommodation chamber is directly heated and the temperature of its inside rises, and the temperatures of the sample to be measured and the reference material, which are accommodated, rise. Further, this heat is transmitted from the accommodation chamber to the cooling block while passing through the heat resistor. In other words, the heat resistor becomes the flow passage, i.e., the heat flow path, of the heat flowing between the accommodation chamber and the cooling block. Further, in a case where the cooling block having been supported by the support means has been cooled to a predetermined temperature (e.g., about -190.degree. C.), since the heat is efficiently heat-exchanged, it is possible to rapidly cool the sample to be measured and the reference material, which are accommodated in the accommodation chamber. Like this, by opportunely performing the heating and the cooling, it is possible to widen a temperature range, and there can be made a desired temperature condition in a short time. [0017] Especially, if the heating and the cooling are repeated, it follows that the accommodation chamber, the heat resistor and the cooling block respectively repeat an expansion and a contraction. On this occasion, since the accommodation chamber, the heat resistor and the cooling block generally differ respectively in their thermal expansion coefficients, there occur a distortion, a positional deviation and the like in a mutual joint face, i.e., a joint face between the heat resistor and the accommodation chamber, and a joint face between the heat resistor and the cooling block. [0018] However, since there is possessed the fixation means of at least any one of the first fixation means or the second fixation means, it is possible to nullify the defect resulting from the distortion, the positional deviation and the like, which have been mentioned above. That is, in a case where there has been possessed the first fixation means, the heat resistor is fixed under a state having been pressed to the cooling block while being biased by a constant elastic force. Therefore, by the difference in thermal expansion coefficient between the heat resistor and the cooling block, even if the heat resistor is distorted with respect to the cooling block or the positional deviation and the like occur, it is possible to buffer a stress resulting from these by the elastic force. In other words, by absorbing the stress resulting from the distortion and the like by the elastic force, a fixation state between the cooling block and the heat resistor can be always maintained to a constant state. [0019] Further, in a case where there has been possessed the second fixation means, the accommodation chamber is fixed under a state having been pressed to the heat resistor while being biased by a constant elastic force. Therefore, by the difference in thermal expansion coefficient between the accommodation chamber and the heat resistor, even if the heat resistor is distorted with respect to the accommodation chamber or the positional deviation and the like occur, it is possible to buffer a stress resulting from these by the elastic force. Therefore, similarly, a fixation state between the accommodation chamber and the heat resistor can be always maintained to a constant state. [0020] Like this, since there is possessed the fixation means of at least any one, even if the heating and the cooling are repeated, differing from conventional one, it is possible to always stably maintain the heat flow path of at least any one of between the heat resistor and the accommodation chamber or between the heat resistor and the cooling block. As a result, it is possible to certainly obtain a heat flow difference signal having the reproducibility. Therefore, it is possible to highly precisely measure the sample to be measured, and the reliability can be improved. [0021] Incidentally, it is desirable to simultaneously possess both the fixation means. [0022] Further, a differential scanning calorimeter of the present invention is one characterized in that, in the above differential scanning calorimeter of the present invention, the first fixation means possesses a through-hole penetrating an upper face and a lower face of the cooling block, a shaft body which is movably inserted into the through-hole, whose one end is fixed to the heat resistor, and whose the other end protrudes to an outward from an inside of the through-hole, a nut meshed with the other end side of the shaft body, and a coil spring which is covered to the shaft body so as to surround a periphery of the shaft body under a state having been nipped between the meshing body and the cooling block, and biases the shaft body toward the other end side by an elastic force, and the elastic force of the coil spring is made adjustable by moving the nut by a mesh in an axial direction of the shaft body. Continue reading... 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